Various types of implantable medical electrical leads for use in cardiac rhythm management and neurostimulation are known. In cardiac rhythm management applications, for example, pacemaker or defibrillator leads are sometimes used to provide an electrical stimulus to a patient's heart and/or to sense cardiac electrical activity occurring within the body. Such leads are typically advanced intravascularly to an implantation location on or within the patient's heart, and are coupled to a pulse generator or other implantable device for delivering electrical stimulus energy to the leads. The leads are typically constructed to have a minimal profile to facilitate insertion of the lead through the body during implantation, and are often flexible to accommodate natural patient movement of the lead at the implantation site.
Implantable medical electrical leads used in cardiac and neurological applications often include an elongate, tubular sleeve that serves to electrically insulate the interior components of the lead from the surrounding body tissue and blood, and which provides additional mechanical strength to the lead. In some lead designs, a portion of the sleeve may be connected proximally to a terminal connector that connects the proximal end of the lead to the pulse generator. Portions of the sleeve may also be connected to a number of electrodes on the lead that deliver electrical stimulus energy to adjacent body tissue.
The attachment of the sleeve to the terminal connector is typically accomplished by application of various biocompatible adhesives to the connector and the sleeve, in some cases in conjunction with a crimping process. The attachment of the sleeve to the electrodes, in turn, is typically accomplished using an adhesive alone and without crimping in order to maintain the desired flexibility of the lead. In use, the adhesive joints that connect the sleeve to the terminal connector and electrodes must offer adequate strength and sealing properties over the operational life of the lead.